. Bonner zoologische Monographien. Zoology. 45 tions ( Wunderer 1909; Häfeli 1971; Guex & Greven 1994). In the 3. ScHWALBE stage, when the offspring measures already 4-5 cm in length and shows signs of metamorphosis, another source of food is necessary. The uterine "milk" that is secreted by the epithelium starting with the 2. Schwalbe was assumed to be an important source (Vilter & Vilter 1964; Niederl 1981), more essential, however, is the zona trophica at the anterior end of the uterus. Here epithelial cells proliferate and become detached from the underlying connectiv
. Bonner zoologische Monographien. Zoology. 45 tions ( Wunderer 1909; Häfeli 1971; Guex & Greven 1994). In the 3. ScHWALBE stage, when the offspring measures already 4-5 cm in length and shows signs of metamorphosis, another source of food is necessary. The uterine "milk" that is secreted by the epithelium starting with the 2. Schwalbe was assumed to be an important source (Vilter & Vilter 1964; Niederl 1981), more essential, however, is the zona trophica at the anterior end of the uterus. Here epithelial cells proliferate and become detached from the underlying connective tissue, probably by necroses and/or apoptotic processes, float within the uterus and were then ingested by the offspring. Young positioned with their head to the nutritive zone scrape off cells from this area with the help of special toothed areas ("Zahnfelder") of the upper and lower jaw. Thus, often more than half the area of the zona trophica is free of epithelial cells and even blood vessels will be opened (Fig. 10a,b). The cells of the trophic zone did not accumulate glycogen or lipids. Fig. 10 a, b. The zona trophica in Salamandra atra. a Note large epithelial cells (arro- wheads), and areas devoid of epithelial cells (arrows) (1 |im semithin section, Toluidine blue-borax), b Scanning electron micrograph of the trophic zone showing an intact epithelium (in the front) and areas free of epithelial cells (in the back). Bar 500 | Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Bonn, Zoologisches Forschungsinstitut und Museum Alexander Koenig
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Keywords: ., bookcentury1900, bookcollectionbiodiversity, booksubjectzoology
